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Ignition timing per gear, why?

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Its motorcycle tuning that i do - buy my question is, why do you have different ignition maps per gear? Surly ignition timing in 3rd at 4K RPM should be the same ignition timing in 5th gear at 4K RPM?

I suspect it is torque limiting for anti-wheelstand/traction considerations. At least on the few modern superbike engines I have played with using OEM ecu's I found not only the advance is soft in low gears but throttle target is very low also - like 30-40% max throttle in first gear etc.

Hello,

This strategy has been used since the early EFI bikes 20 years ago and is there for a couple of reasons;

Primary to account for the greater torque multiplication in lower gears and improve driveability - it helps achieve some linearity for the tractive force giving the rider predictable torque progression. In addition to this it gives the driveline an easier time extending the life of cush drives, chain and sprockets etc. similar results can now be achieved by PPS/TPS mapping with the FBW throttle so its no longer that necessary. With competition bikes its often the case that 1st gear is 'geared out' so that its not used as going into 1st means shifting the barrel through neutral which could create issues on track so again IGN-T by gear is less vital.

Great thanks guys....so essentially its for torque reduction for both drive-train longevity and rid-ability.

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